Electrode materials for the anodes of nickel-metal-hydride rechargeable batteries: The electrodes based on substituted compounds of the AB(5) type

The discharge capacity of electrode materials based on the LaNi2.5Co2.5, LaNi2.5Co2.4Mn0.1, La0.8Ce0.2Ni2Co3, La0.7Nb0.3Ni2.5Co2.4Cr0.1, MmNi(3.5)Co(0.7)Al(0.8), and Mm(0.5)La(0.5)Ni(2)Co(3) intermetallic compounds (IMC) with copper and polytetrafluoroethylene binders is determined. The IMC hydrides, which are stable at room temperature and atmospheric pressure in 1 M NaOH, are shown to contain 2.4 to 4.2 hydrogen atoms per each formula unit of the alloys. It is established that a partial replacement of La with Ce makes no impact on the capacity and lifetime of the electrodes. Introducing Nb into the alloys and increasing La content in a mixture of rare-earth metals make the discharge capacity of the electrodes significantly diminish. Activation modes preceding the measurements are suggested. The overvoltage during the electrode discharge and the capacity attained during this process are found to be determined by the binder nature rather than the alloy nature. At the same discharge currents, the overvoltage is lower and the capacity is higher for the electrodes with the Cu binder. The La0.8Ce0.2Ni2Co3 and MmNi(3.5)Co(0.7)Al(0.8) alloys offer promise as metal-hydride anodes of nickel-metal-hydride rechargeable batteries.